CCNA Practice Exam Test Sample – Question 59

Refer to the exhibit.
Which statement is true?

A. The Fa0/11 role confirms that SwitchA is the root bridge for VLAN 20.
B. VLAN 20 is running the Per VLAN Spanning Tree Protocol.
C. The MAC address of the root bridge is 0017.596d.1580.
D. SwitchA is not the root bridge, because not all of the interface roles are designated.

Correct Answer: D
Section: LAN Switching Technologies

Only non-root bridge can have root port. Fa0/11 is the root port so we can confirm this switch is not the root bridge ->.
From the output we learn this switch is running Rapid STP, not PVST ->.
0017.596d.1580 is the MAC address of this switch, not of the root bridge. The MAC address of the root bridge is 0017.596d.2a00 ->.
All of the interface roles of the root bridge are designated. SwitchA has one Root port and 1 Alternative port so it is not the root bridge.